The present invention concerns a manual control device for a watch and more particularly a device of this type including a bolt sliding on the external surface of a watch case, in particular for controlling or setting a repeater mechanism.
FIG. 1 shows a control device for a watch of the aforementioned type belonging to the prior art and corresponding to Swiss Patent No. 672 868. This control device includes a bolt 2 sliding on the external surface 4 of a watch case 6 and mechanically connected through an oblong opening 8, made in case 6, to a sliding block 10 which co-operates with the arm of a rack (not shown) for controlling the striking work of a repeater mechanism. A sealing gasket 12 is arranged between the sliding block 10 and the inner wall 14 of case 6. This control device further includes means 16 for locking bolt 2 which can be moved in relation to the latter, between a first position in which gasket 12 is compressed between sliding block 10 and wall 14 to assure sealing of the control device, and a second position in which gasket 12 is not compressed and allows the movement of bolt 2 with respect to case 6 to cause the repeater mechanism to strike. Bolt 2 includes a groove 18 in which slides a locking member 20. This member 20 includes a stop 22, an oblong hole 24, a portion of small thickness 26 extending into bolt 2, connected via a ramp 28 to a thicker portion 30 which emerges from bolt 2. A screw 32 connects, through wall 14 and hole 24, bolt 2 to sliding block 10, a self-lubricating pad 34 being inserted between member 20 and bolt 2. A gasket 36 is also provided between the head of screw 32 and sliding block 10. In FIG. 1, bolt 2 is in the rest position, gasket 12 is compressed and bolt 2 cannot be moved. In order to cause the repeater mechanism to be set, the user moves member 20 with his nail in the direction of arrow F with respect to case 6 and bolt 2 until stop 22 comes into contact with pad 34. Portion 26 of member 20 is then at right angles to pad 34, gasket 12 is decompressed and bolt 2 can be moved in the opposite direction to arrow F, driving with it sliding block 10, which sets the repeater mechanism. When bolt 2 is released, it is brought into the rest position by return means, causing during the movement thereof actuation of the repeater mechanism and, thereby, the successive striking of the hours, quarters and minutes in the case of a minute-repeater.
This device however poses the significant risk of bolt 2 becoming locked before having reached its rest position during its return to such position, thus leading to incomplete striking of the minutes, the quarters and even the hours. The significant surface area of gasket 12 as well as the nature of the material of which it is made, in this case neoprene, has a significant friction coefficient with respect to wall 14, which is liable to block bolt 2 in an intermediate position if the latter is not accompanied manually. This risk is further increased by the presence of ramp 28 which pad 34 has to raise again for bolt 2 to return to its rest position.
Moreover, the control device compels the user to exert a relatively large force on the locking member in order to release bolt 2, at the risk of hurting himself, or breaking his nail.